\begin{tikzpicture}[text width=2cm, minimum height=0.5cm]
	\node (haw) [apribox]                     {Hardware};
	\node (vmm) [bluebox, above=0.1cm of haw] {VMM};
	\node (vim) [greenbox, above=of vmm]      {Virtual Machine};

	\draw[arrow] (vmm) to (vim);
\end{tikzpicture}
